Drafting machine attachment



April 1.968 e. M. PELHAM 3,375,588

DRAFT ING MACHINE ATTACHMENT Filed Dec. 13, 1965 ZSheets-Sheet 1INVENTOR.

GIE'OEG-E M. PELHAM A TTOAPA/EV April 2, 1968 G. M. PELHAM 3,375,588

DRAF'TING MACHINE ATTACHMENT Filed Dec. 15, 1965 2 Sheets-Sheet 2 INVENTOR.

. 45026; M. PEI/MM Patented Apr. 2., 1968 3,375,588 DRAFTING MACHINEATTACHMENT George M. Pelham, 7058 12th Ave. NW., Seattle, Wash. 98107Filed Dec. 13, 1965, Ser. No. 513,307 5 Claims. (CI. 33-79) ABSTRACT OFTHE DISCLOSURE A drafting device is disclosed for use with a draftingboard having a parallel motion drafting machine mounted thereon. Thedrafting device is attached to the machine and has a long plate-likebody which is also wide in relation to its length from end to endthereof, and which rests face down on the surface of the board, so thatone end portion thereof is interposed between the head assembly of themachine and the board and carries the weight of the assembly thereon.There are means on the upper side of the body for afiixing it to theinstrument carrier on the head assembly, and means on the undersidethereof for easy sliding movement of the body on the surface of theboard, so that the body moves in translation and rotation on the surfaceof the board, with the instrument carrier, when the carrier is driven inrelation to the board. The other end portion of the body projects outover the surface of the board, free from the assembly, and issufliciently rigid with respect to the weighted end portion thereof tomaintain a flat, level posture on the surface of the board by virtue ofthe moment imparted to the body by the weight of the assembly. There arethree edges on the projecting end portion of the body, two of which areparallel to one another and joined by the third edge which co-terminatesat a right angle with each of the aforesaid two edges. Each of the threeedges is of suificient length to constitute an elongated ruling edge fordrafting purposes, so that orthographic work can be carried out with thedevice alone, while isometric work is effected with the rotationalfeature of the instrument carrier. Preferably, the projecting endportion of the body also has an opening therethrough, opposite theboard, to receive a template member for use with the device.

This invention relates to drafting devices of th nature of straightedges, templates, and the like. While the invention is suitable for usewith .a common T-square, it is particularly adapted as an attachment fora parallel motion drafting machine whereby it is shiftable intranslation with the head of the machine over the surface of a draftingboard.

Parallel motion drafting machines are of several types and, to myknowledge, the invention can beused with all of them. Reference can bemade to US; Patents 2,900,- 728 and 3,153,284 for two such types. Ineach case, it will be noted that the machine includes a shiftable headassembly to which a device is attached. for the draftsmans use. In atypical case, the device is that shown in the patents, namely, a pair ofscales or rules arranged at right angles to one another. The scales orrules are carried on a so-called instrument carrier which is journaledcoaxially with a reference member in the head assembly so as to berotatably adjustable with respect to such member. The.

reference member is rotationally fixed with respect to the anchoringmechanism of the machine so as to maintain a fixed attitude with respectto the board when in translation. For purposes of such translation, itis necessary that the instrument carriers attitude also be fixed.Accordingly, it is releasably engageable with the reference member to be.driven with it when there is translation.

Thus, when the head assembly is shifted in translation over the surfaceof the board, the scales or rules are maintained in a fixed relationshipto the board; and yet when it is desired to do so, the instrumentcarrier can be disengaged from the reference member and rotated aboutits axis to index the scales at any given angle. Ordinarily, auto stopsare provided on the reference member at uniformly spaced angles toprovide for positive indexing of the carrier. The interval betweenangles is usually 15, and a control knob or wheel is furnished on thehead assembly for rotating the carrier between stops.

A ccordingto conventional practice, the scales are used not only asrules for developing straight lines, but also as a reference againstwhich to arrange those template members (and triangles) which thedraftsman may have occasion to use. In general this practice is notattended with many problems. There is one aspect of it, however, whichis troublesome: The scales are not altogether rigid under the pressureof the draftsmans pencil or pen and it is often necessary to steady themwith the other hand when executing a stroke. As seen in the patents,each of them is cantilevered from the instrument carrier and there is nomeans other than ones hand for holding them flat on the drawing boardand preventing them from undergoing lateral deflection. This is alsotrue when using the scales as a reference for triangles and templatemembers. Here again, the draftsman must use his other hand to steady thedevice and/or the scales while executing a stroke.

The necessity for using both hands when executing the steps of adrafting operation may not appear to be particularly troublesome atfirst blush. However, when one remembers that a draftman must also useone hand to operate the machine, that is, to shift the head over theboard and to rotate the instrument carrier about its axis, then thenecessity for using two hands to execute each stroke takes on greatersignificance. For, each time there is a change made, and then a strokeexecuted, it is necessary for him to shift one hand back and forthbetween the control knob and the working area of the board. To avoidthis continual shifting of one hand, many draftsmen resort to usingtriangles with thescales, and some do so to the extent that they seldomrotate the scales from the normal position. This, of course, defeats thepurpose of the machine, at least with regard to the rotational featureof the head. I

Consequently, with this drawback in mind, one object of my invention isto provide a drafting device which,

when attached to a parallel motion drafting machine, e11

ables a draftsman to produce any graphic representation with which hemay be concerned, by the use of a single band and without the help ofhis other hand, throughout the entire operation. Thus, his other hand isfree to .operate the control knob on a continuous basis, for there is nonecessity that it be removed at any time during the operation. Anotherobject is to provide an attachment of this nature which can be used tospeed up the drafting operation and to reduce its manipulative aspectsto a minimum. It is also an object of the invention to provide anattachment which makes the operationmore reliable and exact'byintroducing a greater degree "of mechanical control into the positioningof the ruling edge. A still further object is to provide an attachmentwith these features which increases the versatility and usefulness ofthe machine by furnishing it with elements which are relativelyshiftable with respect to the instrument carrier. Thus the machine cantake on an added degree of relative motion which enables the finaladjustment to be made at the ruling edge rather than in the headassembly. Other objects will become apparent from the descriptionfollowing, including certain which relate to a unique form of scale foruse with the attachment. In the description, I

shall refer to certain embodiments of the invention and shall describethem in detail for purposes of illustrating the invention, but it shouldbe understood that I do so with no intention of limiting it to theseembodiments.

In brief, the invention realizes the above objects by providing anattachment which has a long, Wide platelike body that is intended torestvin parallel relationship on the surface of the board, to move intranslation and rotation thereover, conjointly with the instrumentcarrier on the machine. The attachment is afiixed to the carrier so thatone end portion of its body extends under the head assembly and carriesthe weight of the assembly thereon. The remainder of its body projectsout over the surface of the board from the assembly, and is sufficientlystiff with respect to its weighted portion, to maintain a fiat, levelposture on the board by virtue of the moment imparted by the weight ofthe assembly.

To carry out the drafting operation, there are two edges on theprojecting portion of the attachment which are disposed at a right angleto one another and of sufficient length in each case to constitute anelongated ruling edge for drafting purposes. This is to say, the twoedges are of sufficient length to provide the usual vertical andhorizontal straight edges that are ordinarily furnished .to a draftsman.In addition, the projecting portion of the attachment has an openingtherethrough on a perpendicular to the surface of the board, which isadapted to receive a template member for use with the attachment, theparticular member being a matter of whatever shape the draftsman has inmind, that is, a circle, a triangle, an ellipse, or any of the manyshapes which enter into a graphic representation. The template membermay also serve to produce straight lines in the same manner as thestraight edges, but in adjustable relationship to such edges for reasonswhich will be explained hereinafter.

The template member may simply rest within the opening, so as to befixed in position with respect to the straight edges; or it may bemovably mounted in the opening so as to be shiftable between alternativepositions therein. Preferably, the member is slidably engaged in theopening so that any movement of the attachment produces a correspondingmovement in the template member when the carrier is shifted or rotatedover the board. In this way, the draftsman can grip the control knobwith one hand for purposes of manipulating the carrier, and can rely onthe motion of the knob alone to position the template hole of his choiceover the working area of the board. Moreover, if the template member issufficiently tightly engaged in the opening, he can rely on it to notundergo deflection when he applies his pencil or pen, even though themember remains slidable under the greater pressure of his hand when hechooses to shift its position in the opening.

The invention will be better understood by referring to the accompanyingdrawings wherein I have illustrated the aforementioned embodiments. Ineach case, the template member is slidably engaged in the body of theattachment, but at the same time capable of flexure so as to allow it tobe disengaged from the same.

In the drawings FIGURE 1 is a perspective view of a rectangularattachment which is equipped with a circle template device. The headassembly of the drafting machine is shown in phantom for clarity ofillustration.

FIGURE 2 is a plan view of the attachment in FIG- URE 1.

FIGURE 3 is a cross-sectional view of the attachment along the line 3-3of FIGURE 2.

FIGURE 4 is a part cross-sectional view of a modified form of theattachment in FIGURES 1-3.

FIGURE 5 is a plan view of the attachment in FIG- URES 1-3 as seen inuse with a different form of template device.

FIGURE 6 is a part perspective view of a different form of attachmentthat employs a rotatable template device.

' FIGURE 7 is a part cross-sectional view of the differing form ofattachment seen in FIGURE 6.

And finally, FIGURE 8 is a part perspective view of anadhesively-applied scale which can be used,inter-:

chaugeably, with any attachments made in accord with the invention.

The head assembly seen in FIGURE 1 is of known type and for this reasonis illustrated in phantom only. It includes a reference member12 whichis shiftable in translation over the surface of the board, butrestrained from rotation with respect to the board by a mechanicallinkage mechanism which terminates in an anchoring mechanism (not shown)fixedly mounted on the board. The linkage mechanism comprises a systemof pulleys and flexible bands, the terminal pulley and band of which canbe seen at 4 and 6, respectively. The head assembly also includes aninstrument carrying member 8 which is journaled coaxially with thereference member so as to be rotationally adjustable with respect to thesame, but

which is also releasably engageable with the reference member so as tobe rotatably driven thereby when in translation. The instrument carrieris adjusted with respect to the reference member by operating apush-button 10 which disengages it from the reference member and enablesit to be rotated with respect thereto. A knob 12 1 is shown on top ofthe assembly for this purpose.

Mounted on the instrument carrier is a chuck 14 which typically has apair of legs 16 and 18 that are arranged at a right angle to one anotherand provided with grooves to receive chuck plates on the instrument ordevice to be attached to the machine. For ease of adjusting the devicewith respect to some line or point on the board, the chuck is pivotallymounted on the carrier 8, but capable of being locked in anychosenposition by means of a wing nut 20. The head assembly can also be lockedin position by means of a second wing nut 22.

In accord with the invention, only one .leg of the chuck need be used inattaching the, inventive device to the machine. The device itself iscomprised of a rectangular plate 24 of transparent plastic resinmaterial which has a suitably formed flange or chuck plate 26 secured toits upper side at a position somewhat centrally located of the plasticplate 24 so that the end portions of the latter are disposed to eachside of the chuck plategThe plate 24 is also equipped with a pluralityof buttons 27 on its underside which act as slides when it is in use. Inattaching the device, the left hand portion of the plate 24 is slippedbeneath the instrument carrier and rested on the board, with the headassembly on top of it so that the weight. of the assembly. tends tomaintain its flatness on the board. The remainder of the plate 24projects out from the assembly and provides a pair of scaled edges 28and 30 which are disposed at a right angle to one another for draftingpurposes. Each of the edges is rigidly fixed in relation to the assemblyby virtue of the wide-spreading character of the plate, and the factthat each has a short moment arm about the machine head.

The projecting portion of the plate 24 also has a large opening 32 whichis generally square in cross-sectional area, but extended to the left inthe form of a pair of slots 34 that project in finger-like fashion fromthe corners of the opennig. In use, the opening serves as a frame andguide for a template member 36 which is. formed from a sheet of flexibleplastic resin material and sized to fit slidably into the opening whensubstantially coplanar therewith. In addition, the plate 24 also servesto support the template member, and for this purpose tonguedcross-section 38which is engageable with a rounded recess 40 along theedges of the template member. The member is engaged in the opening byflexing it and releasing it in the opening after it has been insertedand suitably positioned therein. Flexure may be accomplished by bendingthe member cross-wise of its body, or by depressing the upper endportion 29 thereof. In this latter connection, it will be noted that thetemplate member is relieved along its upper edge 29, at both ends, sothat only the center section of the edge engages with the adjacent edgeof the opening. In addition, a transverseslot 46 is provided in themember just behind the edge 29. The reduced length of edge 29facilitates shifting of the member within the opening by reducingfrictional contact between their edges. On the other hand, the slot 46adds sufl'icient flexibility to the edge portion 29 so that it can beflexed in the body plane of the member and inserted and withdrawnconveniently with one hand in a simple pop-in or pop-out procedure.

As an alternative, the upper edge of the template member may be given alipped cross-section such as is seen in FIGURE 4. In this instance, themember 36' has a generally pan-shaped cross-section and is relieved at47 behind its upper edge 29' so that the edge can be depressed in theinward direction by bending about its rim.

For ordinary ruling purposes, the edges 28 and 30 are entirely suitable.However, for small scale work I find that it is preferable to use theupper and lower edges of the opening, including the extensions thereofprovided by the slots 34 which project from the left-hand corners of theopening. In such a case the member 36 may be removed from the openingor, in the alternative, it may be rotated through 90 and reinsertedbetween the right and left hand edges of the opening so that the upperand lower edges of the same are free for ruling purposes.

When it is desired to draw something other than a straight line, thedraftsman must select from the holes 44 in the template member tosatisfy his need. The holes in this case are circular and as such asrepresentative of the various sizes and shapes of templates with which adraftsman is concerned. In this sense, then, the template member is onlyrepresentative of a broad selection of such members which can be used onan interchangeable basis within the attachment.

Because the attachment is Weighted down by the machine head and highlyinflexible to deflection by the draftsmans tool, the draftsman canmaintain one hand on the control knob at all times and has the otherhand free for shifting the template member, exchanging it for another,or putting his pen or pencil to use. If he wishes to have a templatemember which is adjustable in both t He horizontal and verticaldirections, he can make use of a member such as is seen in FIGURE 5. Inthis case the member is in two parts, one of which serves as a slidableframe for the other. The sliding frame section is seen at 48 and asindicated by arrow 50 is slidable in the horizontal direction within theopening of the plate 24. The template section is seen at 52 and isslidable in the vertical direction within the frame section. See arrow54. Between them, the two sections enable the draftsman to quickly aligna template with the board below, and by introducing a further element ofrelative movement, the member enlarges considerably on the mobility andversatility of the basic machine.

The aforementioned embodiments also have additional advantages which canbe explained with reference to the figures. Note for example in FIGUREthat the upper edge 56 of the template section provides a ruling edgethat is adjustable with respect to the adjacent edge 58 of the framesection. I have found that these edges are particularly advantageous informing pairs of lines to act as lettering guides on a drawing. The sameis also true of the relatively shiftable edges of the frame section andthe plate in FIGURE 5; and if the template member in FIGURE 2 is rotatedthrough 90 and reinserted, it too can be used 6 for this purpose inconnection with the upper edge of the plate opening. 1

I have also found that the opposing edges of the plate opening, or theopening in the frame section of the template member in FIGURE 5, providea pair of auto stops with which to automatically relate various templateholes when drawing certain composite symbols in technical drafting. Forexample, the symbol for a particular type of valve in technical draftingis that is, a pair of triangles joined at their apexes. In FIG- URE 5this symbol can be developed quite quickly and simply by shifting theframe section to the right after the right hand of the two trianglesindicated at 60 is developed. Of course, the same is also true whendeveloping guide lines for lettering if the shift allowed the templatemember is equated with the height of the lettering.

A still further advantage can be derived from the fact that one or twoedges of the template member can be canted with respect to the edges ofthe opening. In FIG- URE 2 for example, the right hand edge 62 of thetemplate member is canted at a 7 /2 angle with respect to the lower edgeof the opening. This enables the draftsman to increase twofold thenumber of indexing angles which can be developed from a conventionalmachine, which typically uses a 15 interval between auto stops. Ofcourse, any other angle can be used and by canting the left hand edge 64of the template member as well, it is possible to subdivide the autostop intervals even further.

A third form of template member can be seen in FIG- URE 6. In this casethe plate 24 is furnished with a circular opening 66 and the templatemember is designed to be angularly related to either the vertical orhorizontal edge of the plate. The template member is in the form of aflat disc 68, the interior of which is slotted along two diametricallines 70 and 72 that intersect at a 60 angle with one another. Tosupport the disc, the edge of the opening is rabbitted to form a seat 74on which the disc can rest. The disc is constructed from a flexibleplastic resin material and if desired, can be manually removed by meansof a pair of holes 76 that are punched or bored through the upper andlower halves of the disc. In most cases, however, the disc remains inplace on a permanent basis.

The disc is releaseably engaged in the opening by means of a pair ofbuttons 78 on its side walls which insert in complementary depressions80 in the rabbitted wall of the opening. See FIGURE 7. Because of itsflexibility, the disc is rotatable in the opening. Thus, by using theholes 76 to rotate the disc, the slots 70 and 72 can be oriented in anydesired attitude with respect to the edges of the frame member. I havefound that this form of template member is particularly useful indepicting isometric representations where the slot 70 can be arranged onthe vertical after the attachment has been swung through a 30 angle forthe isometric. With slot 70 so fixed, the slot 72 assumes the angle ofthe isometric along its other slope. In this way the draftsman can fixthe attachment at the angle of the isometric and use the slots in placeof triangles that would otherwise be necessary when the indexing actionof the machine head is utilized in this fashion.

Referring once again to FIGURES 1-5, it will be seen that the scale 42on the upper edge 28 of the plate 24 is provided, not directly on theedge in the sense of being imprinted or indented thereon, but instead byway of a strip 82 of flexible material laid along the length of theedge. According to an additional feature of my invention, I prefer tomark each of the ruling edges 28 and 30 in this fashion, in order thatthe scale may be replaced with another when so desired, such as when itis desired to change the type of scale, to increase or reduce itscalibration, or to produce a new one. The strip is conveniently atransparent plastic resin material, such as Mylar, and as seen in FIGURE8, carries an adhesive backing 84, by which it is applied to either theupper side or the under side of the plate after a protective cover strip86 has been peeled away from the adhesive. The markings may be appliedto the strip by a photographic process or by the silk screen printingprocess, each of which is well known. Because of the nature of theinventive attachment, a band-aid type of scale such as this, isparticularly useful; however, it will be appreciated that theillustrated scale may also be employed with other drafting devices, suchas with the rules shown in the above-mentioned patents.

It will also be appreciated that numerous other changes and additionscan be made in and to the invention without departing from the scope andspirit of the same as defined in the-claims following.

I claim:

1. A drafting device for use with a drafting board having a parallelmotion drafting machine mounted thereon, comprising a long plate-likebody which is also wide in relation to its length from end to endthereof, and which rests face down on the surface of the board in use,one end portion of the body having a continuously uninterrupted facialarea thereon adapted to be interposed between the head assembly of thedrafting machine and the board, and to carry the weight of the assemblythereon, and the other end portion of the body having three edgesthereon, two of which are parallel to one another and joined by thethird edge which co-terminates at a right angle with each of theaforesaid two edges, each of the three edges being of sufiicient lengthto constitute an elongated ruling edge for drafting purposes, therebeing means on the upper side of the body for affixing it to theinstrument carrier on the head assembly of the machine, and means on theunderside thereof for easy sliding movement of the body on the surfaceof the board, so that in use the body moves in translation and rotationon the surface of the board, with the instrument carrier, when thecarrier is driven in relation to the board, and an opening in theaforesaid other end portion of the body, to lie opposite the board, saidopening having a platelike template member received therein, whichtemplate member is substantially coplanar with the opening and engagedbetween the edges thereof so as to be supported on the body andnon-movable with respect thereto when ruling through the templatemember, but characterized with sufficient flexibility in at least oneedge portion thereof that it is insertable and removable into and fromthe opening by flexing the aforesaid portion thereof.

2. A drafting device according to claim 1 wherein the template member isshiftable between alternative positions in the opening of the body, bythe application of a force in the plane of the opening which exceedsthat used in ruling.

3. The combination according to claim 1 wherein the template member isslidably engaged between the edges of the opening so that it issupported on the body of the device and any movement of the deviceproduces a corresponding movement in the template member when thecarrier is shifted or rotated over the board.

4. The combination according to claim 2 wherein the body of the devicehas a plurality of stops about the edges of the opening corresponding tothe respective positions of the template member.

5. The combination according to claim 1 wherein the template member iscomprised of two plate-like sections, one of which is slidably engagedin the opening and the other of which is slidablyengaged in a similarfashion in the one section.

References Cited UNITED STATES PATENTS 1,145,922 7/1915 Rigaumont 33-1121,154,673 9/1915 Van Ness 33-75 1,821,369 9/1931 Wetterstrand 33 -1742,428,699 10/1947 Ebert et a1. 33-110 2,742,705 4/1956 Gelardi 33-1372,842,849 7/1958 Amery 33-79 1 2,932,897 4/1960 Huber 33-137 3,103,7479/1963 De La Sierra 33-174 3,279,074 10/1966 McQuaid 33-104 HARRY N.HAROIAN, Primary Examiner.

LEONARD FORMAN, Examiner.

